1. Field of the Invention
The invention relates generally to motor vehicle safety systems and methods, and specifically to warning systems and methods having means onboard the motor vehicle for developing warning signals from magnets or similar devices affixed on a roadway over which the vehicle is passing so as to warn a driver of the vehicle of an oncoming hazardous driving condition.
2. Background Art
On a national basis, most fatal motor vehicle accidents occur during nighttime driving. A major contributing factor to these motor vehicle accidents is driver inattentiveness and in particular the driver's inappropriate actions. The driver needs a warning that the present or approaching condition warrants more attention. The warning must be sufficient to encourage the driver to pay more attention to the driving task.
A number of systems have been proposed for the control of motor vehicles along a roadway through the use of sensors on the vehicle which cooperate with signal devices on the roadway for determining the position of the vehicle. The signal devices on the roadway have taken the form of electrical wires or magnetic material embedded in the roadway surface at predetermined positions along the roadway. The sensors are positioned on the vehicle to detect the proximity to the signal area of the roadway using as an example, magnetic pickup devices. The proximity of the vehicle is then determined and electronic systems used to provide control commands to the vehicle. The complexity and cost of such systems has been blamed for their lack of use.
U.S. Pat. No. 3,609,678 to Fayling discloses a magnetized means for providing control information to vehicles traveling on the roadways. The magnets disclosed are polymer-based magnets which comprise a tough organic polymeric matrix and particles of magnetic material uniformly distributed through the matrix. The magnets are installed in the form of a sheet or tape in a channel formed in the roadway surface and are arranged in geometries or are magnetized in patterns to develop information-providing signals in magnetic flux sensors in vehicles traveling over the magnets.
U.S. Pat. No. 4,401,181 to Schwarz discloses a road vehicle control system for use with a roadway having magnetic marking elements. The magnetic elements define the lanes of travel and zones of lower speed on the roadway. A plurality of sensors mounted on the motor vehicle detect proximity to the marking elements and a connected control means produces control signals corresponding to the position of the vehicle with respect to the lane of travel and also of the presence of a lowered speed zone. Circuitry is disclosed for developing speed command signals for operating a steering servo and speed control commands to a speed servo. In one embodiment an array of four sensors is positioned along the width of the motor vehicle and a variable connecting means is provided so that the left and right sensors can develop the steering signals for a roadway having lane-edge markers, or the center two sensors can provide steering signals for use on a roadway having lane center marking elements.
In another speed control device, U.S. Pat. No. 4,173,010 to Hoffmann discloses a traffic sign and system for recording vehicle speed which uses positioning sensors adjacent a roadway. The sensors comprise pressure switches connected to two speed hoses to be run over, as in a traffic counter. Photo-optical, acoustical or magnetic sensors are also suggested. The sensors are spaced a predetermined distance apart in the direction of travel, and provide information to a logic system to measure the speed of vehicles traveling along the roadway. The logic system is connected to a simple readout sign displayed for observation by drivers of vehicles along the roadway, which sign indicates whether a vehicle is traveling at a proper rate, or too fast, or too slow, or too close to a preceding vehicle. The patent also discloses a modified motion picture camera provided adjacent the roadway to film a vehicle that is moving too rapidly, and a modified film editing device is provided for counting the frames exposed and thereby determining the speed of the vehicle.
U.S. Pat. No. 4,833,469 to David discloses an obstacle proximity detector for use in automobiles that provides a warning signal to both the car and the driver that the automobile is approaching an obstacle at an unsafe speed or is getting too close to the obstacle. The system detects the differential velocity between the car and the obstacle and determines the distance separating the car from the obstacle which may be fixed or moving in a general direction oriented in the same direction as that followed by the system equipped vehicle. A signal is generated whenever the combination of differential velocity and separation distance reaches an unsafe level. This signal is then processed so as to emit various types of signals that can be seen, heard and/or be used for taking emergency action such as causing the vehicle brakes to be applied automatically if the driver does not heed the passive signals already emitted.